Add Unsafe based storage backend

Summary:
@public

Adds another version of property storage for `YogaNode`, using `sun.misc.Unsafe`.

Adopts the stub concept from Litho for `Unsafe`, as it is hidden by the Android SDK.

Reviewed By: pasqualeanatriello

Differential Revision: D9140103

fbshipit-source-id: a4b376eca341b724a00f873467ae8bf8eaac69f4

java/com/facebook/yoga/YogaNode.java

@@ -23,6 +23,7 @@ public class YogaNode implements Cloneable {
 
   public static final int BYTE_BUFFER = 1;
   public static final int HYBRID = 2;
+  public static final int UNSAFE = 3;
 
   /** Get native instance count. Useful for testing only. */
   static native int jni_YGNodeGetInstanceCount();
@@ -50,6 +51,9 @@ public class YogaNode implements Cloneable {
       case HYBRID:
         mDelegate = new YogaNodePropertiesHybrid(this);
         break;
+      case UNSAFE:
+        mDelegate = new YogaNodePropertiesUnsafe(this);
+        break;
       default:
         mDelegate = new YogaNodePropertiesJNI(this);
     }
@@ -63,6 +67,9 @@ public class YogaNode implements Cloneable {
       case HYBRID:
         mDelegate = new YogaNodePropertiesHybrid(this, config);
         break;
+      case UNSAFE:
+        mDelegate = new YogaNodePropertiesUnsafe(this, config);
+        break;
       default:
         mDelegate = new YogaNodePropertiesJNI(this, config);
     }